Semiconductor substrates with unitary vias and via terminals, and associated systems and methods

ABSTRACT

Semiconductor substrates with unitary vias and via terminals, and associated systems and methods are disclosed. A representative method in accordance with a particular embodiment includes forming a blind via in a semiconductor substrate, applying a protective layer to a sidewall surface of the via, and forming a terminal opening by selectively removing substrate material from an end surface of the via, while protecting from removal substrate material against which the protective coating is applied. The method can further include disposing a conductive material in both the via and the terminal opening to form an electrically conductive terminal that is unitary with conductive material in the via. Substrate material adjacent to the terminal can then be removed to expose the terminal, which can then be connected to a conductive structure external to the substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No. 12/253,121filed Oct. 16, 2008, now U.S. Pat. No. 8,030,780, which is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The present disclosure is directed generally to semiconductor substrateswith unitary vias and via terminals, and associated systems and methods.

BACKGROUND

Packaged semiconductor dies, including memory chips, microprocessorchips, and imager chips, typically include a semiconductor die mountedto a substrate and encased in a plastic protective covering. The dieincludes functional features, such as memory cells, processor circuits,imager devices, and interconnecting circuitry. The die also typicallyincludes bond pads electrically coupled to the functional features. Thebond pads are electrically connected to pins or other types of terminalsthat extend outside the protective covering for connecting the die tobusses, circuits, and/or other microelectronic assemblies.

Market pressures continually drive manufacturers to reduce the size ofsemiconductor die packages and to increase the functional capacity ofsuch packages. One approach for achieving these results is to stackmultiple semiconductor dies in a single package. The dies in such apackage are typically interconnected by electrically coupling the bondpads of one die in the package with bond pads of other die(s) in thepackage.

A variety of approaches have been used to electrically interconnect thedies within a multi-die package. One existing approach is to use solderballs connected directly between the bond pads of neighboring dies.Another approach is to fuse “bumps” on the bond pads of neighboringdies. However, the foregoing processes can suffer from severaldrawbacks. For example, the foregoing structures typically require amultitude of steps to form the vias, the conductive material in thevias, and the bond pads or other connecting structures that form theconnections between stacked dies. Each of the steps takes time andaccordingly adds to the cost of manufacturing the packaged device. Inaddition, in at least some cases, each of the processes can elevate thetemperature of the die, which can consume a significant portion of thetotal thermal budget allotted to the package for processing. As aresult, there remains a need for improved techniques for interconnectingdies within a semiconductor package.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic, side cross-sectional view of a packageconfigured in accordance with an embodiment of the disclosure.

FIGS. 2A-2I are partially schematic, side cross-sectional views ofsemiconductor substrates undergoing processing in accordance with anembodiment of the disclosure.

FIG. 2J is a partially schematic, side cross-sectional view of twosemiconductor substrates stacked in accordance with a particularembodiment of the disclosure.

FIG. 2K is a partially schematic, side cross-sectional view of twosemiconductor substrates stacked in accordance with another embodimentof the disclosure.

FIGS. 3A-3F are partially schematic, side cross-sectional illustrationsof representative methods for forming substrate terminals having shapesin accordance with further embodiments of the invention.

FIG. 4 is a partially schematic, side cross-sectional illustration of aprocess for disposing a protective layer on a semiconductor substrate inaccordance with a particular embodiment of the disclosure.

FIG. 5 is a schematic illustration of a system that can include one ormore packages configured in accordance with several embodiments of thedisclosure.

DETAILED DESCRIPTION

Several embodiments of the present disclosure are described below withreference to packaged semiconductor devices and assemblies, and methodsfor forming packaged semiconductor devices and assemblies. Many detailsof certain embodiments are described below with reference tosemiconductor dies. The term “semiconductor die” is used throughout toinclude a variety of articles of manufacture, including, for example,individual integrated circuit dies, imager dies, sensor dies, and/ordies having other semiconductor features. Several of the processesdescribed below may be used to connect an individual die to anotherindividual die, or to connect an individual die to a wafer or portion ofa wafer, or to bond a wafer or portion of a wafer to another wafer orportion of a wafer. The wafer or wafer portion (e.g., wafer form) caninclude an unsingulated wafer or wafer portion, or a repopulated carrierwafer. The repopulated carrier wafer can include an adhesive material(e.g., a flexible adhesive) surrounded by a generally rigid frame havinga perimeter shape comparable to that of an unsingulated wafer, withsingulated elements (e.g., dies) carried by the adhesive. The term“semiconductor substrate” is used throughout to include the foregoingarticles of manufacture in any of the foregoing configurations.

Many specific details of certain embodiments are set forth in FIGS. 1-5and the following text to provide a thorough understanding of theseembodiments. Several other embodiments can have configurations,components, and/or processes different than those described in thisdisclosure. A person skilled in the relevant art, therefore, willappreciate that additional embodiments may be practiced without severalof the details and/or features of the embodiments shown in FIGS. 1-5,and/or with additional details and/or features.

FIG. 1 is a partially schematic, side cross-sectional view of asemiconductor assembly 100 that includes a semiconductor package 106configured in accordance with an embodiment of the disclosure. Thepackage 106 can include a support member 102 that carries multiplesemiconductor substrates (e.g., semiconductor dies 101) that areinterconnected electrically and mechanically with each other.Accordingly, each of the semiconductor dies 101 can include dieterminals 110 that are connected to corresponding die terminals 110 ofthe neighboring die 101. The support member 102 can include supportmember terminals 107 that are connected to the die terminals 110 of oneor more of the semiconductor dies 101. The support member terminals 107are connected via lines internal to the support member 102 to packageterminals 104. The entire package 106 (or portions of the package 106)can be surrounded by an encapsulant 103 to protect the semiconductordies 101 and the associated connections between the dies 101, while thepackage terminals 104 remain exposed for connecting the package 106 toexternal devices, such as printed circuit boards and/or other circuitelements. The following discussion describes additional features of theterminals 110 used to connect neighboring dies 101 to each other, andassociated methods for forming such terminals.

FIG. 2A is a partially schematic, side cross-sectional illustration of asemiconductor substrate 120 (e.g., a wafer, wafer portion, die, or othersubstrate) that includes a substrate material 121 having a first majorsurface 123 and an oppositely-facing second major surface 124. As shownin FIG. 2A, multiple vias 140 have been formed so as to extend into thefirst surface 123 along corresponding via axes V. A bond pad can beadded to the semiconductor substrate 120 after the vias 140 are formed(as described later with reference to FIG. 2J), or the vias 140 canpenetrate through pre-formed bond pads at the first surface 123.Individual vias 140 can be axisymmetric with respect to thecorresponding via axis V (e.g., each via 140 can have a circularcross-sectional shape), or the vias 140 can have other cross-sectionalshapes that closely surround the via axis V (e.g., a low aspect ratioelliptical shape). The vias 140 can be formed using techniques such asaniosotropic etching techniques. Each via 140 can include one or moresidewall surfaces 141 and an end surface 142. In some embodiments, thesidewall surfaces 141 can be scalloped, e.g., by using as stepwise Boschetching process. In such cases, the vias 140 can be post-processed(e.g., using SF₆ or another isotropic etchant) to smooth the scallops.However, in particular embodiments, the etching process used to form thevias 140 can be a generally continuous process that produces generallysmooth, unscalloped sidewall surfaces 141. The sidewall surfaces 141 canaccordingly have a generally smooth, cylindrical shape. Suitableprocesses for forming the via 140 include a wet etch process, a steadystate dry etch process, laser drilling, micro-electrodischargemachining, microbead blasting, and others.

The vias 140 are used to house conductive structures that are connectedto semiconductor features (not shown in FIG. 2A) within the substratematerial 121, and terminals used to electrically connect thesemiconductor substrate 120 to other semiconductor substrates and/orsupport members. The following Figures describe further details of theformation of these terminals.

As shown in FIG. 2B, a protective layer 122 has been disposed on thesemiconductor substrate 120 so as to cover the sidewall surfaces 141 andend surfaces 142 of the vias 140. The protective layer 122 can include aC₄F₈ passivation layer, CVD-deposited oxides or nitrides, or othersuitable materials. In FIG. 2C, the portions of the protective layer 122covering the end surfaces 142 of the individual vias 140 have beenremoved, so as to re-expose the end surfaces 142. The portions of theprotective layer 122 over the end surfaces 142 can be selectivelyremoved, e.g., without removing the portions of the protective layer 122adjacent to the sidewall surfaces 141. For example, an anisotropicremoval process can be used to selectively remove this material. Arepresentative removal process includes a spacer etch, or other etchprocess that selectively removes horizontally-oriented materials.

In FIG. 2D, terminal openings 111 have been formed at the ends ofindividual vias 140. In general, the terminal openings 111 are formedwithout affecting the shapes of the vias 140 above, due to theprotective function performed by the protective layer 122 that coversthe sidewall surfaces 141. The terminal openings 111 can have shapesdifferent than those of the via 140. For example, while the vias 140 mayhave a generally cylindrical shape, the terminal openings 111 can have agenerally spherical shape. The terminal openings 111 can also extendlaterally beyond the width of the via 140, for example, by using anisotropic removal process as opposed to an anisotropic removal process.Further representative techniques for forming such structures areincluded in an article titled “Micromachining of Buried Micro Channelsin Silicon” (de Boer, et al., Journal of Micro ElectromechanicalSystems, Vol. 9, No. 1, March 2000), incorporated herein by reference.After the terminal openings 111 are formed, the portions of theprotective layer 122 extending into and between the vias 140 are removedprior to subsequent steps for applying conductive material in both thevia 140 and the terminal opening 111, as described below.

FIG. 2E illustrates the semiconductor substrate 120 after additionalmaterials have been disposed thereon. For example, as shown in FIG. 2E,a dielectric layer 125 has been disposed on the first surface 123 of thesubstrate material 121, as well as in the vias 140 and the terminalopenings 111. A barrier layer 126 has been disposed on the dielectriclayer 125, and an optional seed layer 127 has been disposed on thebarrier layer 126. Suitable dielectric materials include TEOS, parylene,nitrides, oxides and/or other suitable materials. Suitable barrier layermaterials include tungsten, titanium nitride, tantalum, compounds of theforegoing materials and/or other suitable materials. In someembodiments, the seed layer 127 is used to facilitate the process offilling the vias 140 and the terminal openings 111. In otherembodiments, a direct on barrier plating process can be used to achievethe same result.

FIG. 2F illustrates the semiconductor substrate 120 after a conductivematerial 112 has been disposed in the vias 140 and the terminal openings111. The conductive material 112 can be disposed in both the vias 140and the terminal openings 111 using a bottom-up deposition process orother suitable process to form a unitary conductive structure 119 thatfills both the vias 140 and the terminal openings 111. This single-stepprocess can be performed without realigning the semiconductor substrate120 between the operation of forming the conductive material 112 in thevia 140 and the operation of forming the conductive material 112 in theterminal opening 111. This operation can also be performed without theneed to form a vent hole at the end of the via 140, which furtherreduces processing time.

Suitable techniques for introducing the conductive material 112 into thevia 140 and terminal opening 111 include but are not limited to pulsedchemical vapor deposition (pCVD), ionic physical vapor deposition(iPVD), atomic layer deposition (ALD), electro-grafting, bottom-up ECDplating, and electroless plating. Suitable conductive materials includecopper, aluminum, tungsten, gold and/or alloys of the foregoingconstituents. In particular embodiments, the conductive material 112 isselected to be electrolytic copper, which has enhanced purity whencompared to electrolessly disposed materials, and when compared tosolder. For example, the conductive material can be at least 90% copperand in some cases, 99% copper.

In still further particular embodiments, the conductive material 112 issolder free, e.g., it includes no solder or no more than a trace amountof solder. It is expected that such a material selection can produceconductive structures with enhanced conductivity and/or structuralcharacteristics.

In still further embodiments, the conductive material 112 can bepreformed (at least in part) before being disposed in the via 140 andthe terminal opening 111. For example, the conductive material 112 caninclude a pre-formed wire that is inserted into the via 140 using awire-bonding process. In this case, the process described below forremoving material from the second surface 124 of the substrate 120 canbe performed before rather than after the conductive material 112 isdisposed in the via 140.

When the conductive material 112 has been introduced into the via 140and the terminal opening 111 using a build-up technique (e.g., plating),the process can next include removing material from the second surface124 to expose the conductive material 112 in the terminal opening 111.For example, in a particular embodiment, the substrate material 121 canbe removed (e.g., in a backgrinding or other removal process) up to thedashed line L shown in FIG. 2F.

FIG. 2G illustrates a portion of the substrate 120 shown in FIG. 2F,including a single via 140 after the substrate material 121 has beenremoved from the second surface 124. As shown in FIG. 2G, removing thesubstrate material 121 can expose the conductive material 112 to form afirst terminal 110 a. The resulting first terminal 110 a can have awidth W2 that is greater than a corresponding width W1 of the via 140.Accordingly, the first terminal 110 a can include additional exposedsurface area for connecting to adjacent structures. A passivation layer128 can then be disposed on the second surface 124 to protect the secondsurface 124 after the foregoing backgrinding operation.

The dimensions of the via 140 and the first terminal 110 a can beselected depending upon characteristics of the substrate 120 to formhighly conductive, compact electrical paths. For example, for aninitially 800μ-thick substrate 120, the via 140 can be selected to havea depth D1 of less than 100μ (e.g., 50μ or 25μ). The remaining substratematerial 121 can be background, as described above. The width W1 can be20μ or less (e.g., 10μ or 5μ).

In a particular aspect of an embodiment shown in FIG. 2G, the firstterminal 110 a can have an exposed conductive surface 118 that isgenerally flush with the second surface 124 of the substrate material121. Accordingly, the resulting conductive structure 119 in the via 140and the terminal opening 111 extends through the substrate material 121from the first surface 123 to the second surface 124. In otherembodiments, additional substrate material 121 can be removed so as tofurther expose the surfaces of the first terminal 110 a, e.g., to form a“bump.” For example, FIG. 2H illustrates a second terminal 110 b that isformed by removing additional material from the second surface 124 ofthe substrate 120 in the regions surrounding the second terminal 110 b.The substrate material 121 can be removed using a wet etch process, or aplasma dry etch process (e.g., with an SF₆O₂ chemistry). The dielectricmaterial 125 in this region can also be removed. This process canproduce electrically conductive, outwardly facing surfaces 113 that facelaterally outwardly from the via axis V, and project axially away fromthe second surface 124 in a tapered fashion. Accordingly, the outwardlyfacing surfaces 113 can increase the exposed surface area of the secondterminal 110 b (relative to the cross-sectional area of the secondterminal 110 b) available for establishing connections with adjacentdevices. In other embodiments, the outwardly facing surfaces 113 canproject or otherwise extend axially into or against the structures ofadjacent devices to establish electrical and physical connections.

The second terminal 110 b can include conductive materials in additionto the conductive material 112 that fills the via 140. For example, thesecond terminal 110 b can include a flash coating 114 that is applied tothe exposed surface 118. The flash coating 114 can facilitate electricalconnections with adjacent devices. In a particular embodiment, the flashcoating can include tin, gold, indium or other suitable electricallyconductive materials. In general, the flash coating 114 can be appliedusing an electroless processing which does not require the use of amask.

FIG. 2I illustrates a representative third terminal 110 c that alsoincludes conductive materials in addition to the conductive fillmaterial 112. In this particular embodiment, the additional material caninclude a solder ball 115. The solder ball 115 can contact thedownwardly facing exposed surface 118 of the conductive material 112, aswell as the outwardly facing surfaces 113. This arrangement can give theterminal 110 c increased surface area for connecting to adjacentstructures. Because the solder ball 115 extends around the outwardlyfacing surfaces 113, it can provide both increased physical andelectrical continuity with the conductive material 112.

FIG. 2J schematically illustrates a portion of a semiconductor assembly100 that includes a first die 101 a electrically connected to a seconddie 101 b in a stacked arrangement. The dies 101 a, 101 b can includeburied microelectronic elements 130 (e.g., capacitors or transistors)connected to bond pads 132 with lines 131. The bond pads 132 are in turnelectrically connected to the conductive structures 119 in the vias 140.The first die 101 a can include first terminals 110 a generally similarin configuration to those described above with reference to FIG. 2G. Thesecond die 101 b can include second terminals 110 b generally similar inconfiguration to those described above with reference to FIG. 2H. Thetwo dies 101 a, 101 b can be brought together with the first terminals110 a contacting the second terminals 110 b. In one embodiment, theexposed surfaces 118 of individual first terminals 110 a can contact theexposed surfaces 118 of corresponding individual second terminals 110 b.In another embodiment, one or both of the first and second terminals 110a, 110 b can include a flash coating 114 (FIG. 2H) that contacts theother terminal. The terminals 110 a, 110 b can be connected using heat,pressure, and/or other forms of energy (e.g., ultrasonic energy) to fusecorresponding first and second terminals 110 a, 110 b to each other. Forexample, the terminals 110 a, 110 b can be attached without reflowingthe terminal constituents (e.g., by applying pressure, or pressure incombination with ultrasonic energy). Suitable representative processesinclude ultrasonic, thermal-sonic and/or thermal-compression processes.In one embodiment, the second terminals 110 b can project axially beyondthe corresponding second surface 124 of the second die 101 b to engagewith the corresponding first terminals 110 a of the first die 101 a. Insome cases, a gap 105 may remain between the dies 101 a, 101 b in theinterstices among the terminals 110 a, 110 b after the attachmentprocess is complete. The gap 105 can be filled with an underfillmaterial or other suitable material, e.g., prior to encapsulating thestacked structure. In particular embodiments, the completed assembly canhave a configuration generally similar to that shown in FIG. 1.

In FIG. 2J, the first and second dies 101 a, 101 b are stacked so thatthe exposed surfaces 118 of the first terminals 110 a contact theexposed terminals 118 of the second terminals 110 b. In otherembodiments, the relative orientations of one or both dies 101 a, 101 bcan be inverted. For example, in one embodiment, both dies 101 a, 101 bcan be inverted (compared to the orientation shown in FIG. 3J) so thatthe bond pads 132 of the first die 101 a contact corresponding bond pads132 of the second die 101 b, and the exposed surfaces 118 of each die101 a, 101 b face outwardly (e.g., upwardly and downwardly in FIG. 2J).

In another example, shown in FIG. 2K, the orientation of the second die101 b is inverted relative to the orientation shown in FIG. 2J, whilethe first die 101 a retains its orientation. Accordingly, the exposedsurfaces 118 of the first die 101 a contact the bond pads 132 of thesecond die 101 b. This orientation can be used to stack more than twodies in particular embodiments. In other embodiments, the foregoingorientations described above with reference to FIGS. 2J-2K can becombined, e.g., when the assembly includes more than two stacked dies.For example, a third die can be stacked on top of the second die 101 bshown in FIG. 2J, with exposed surfaces of the third die terminals incontact with the bond pads 132 of the second die 101 b.

One feature of at least some of the foregoing embodiments describedabove with reference to FIGS. 1-2K is that the conductive path throughthe via 140 can be formed concurrently with forming the terminal 110 atthe end of the via 140. As a result, the overall conductive structure119 within the via 140 and at the terminal 110 can be generally unitaryand homogeneous. In particular, the same conductive material can fillthe via 140 and the terminal opening 111, without forming a materialboundary within the overall structure 119. This process can accordinglyproduce an overall conductive structure 119 having an increasedcontinuity when compared with existing structures that have boundariesbetween vias and corresponding bond pads. As a result, these structurescan have increased reliability when compared to existing structures.

In addition, the via 140 and the terminal 110 can be formed without theneed for using a mask/lithography process at the second surface 124,which is typically used to form a bond pad or bump at the end of a via.Instead, the structure can be formed using less time-consuming and lessexpensive deposition and selective etch processes. This in turn canreduce the amount of time needed to form the conductive structure 119and therefore the cost of the die or other product in which the via isformed.

Another feature of at least some embodiments of the foregoing processesis that the semiconductor substrates 120 need not be realigned betweenthe operation of filling the via 140 and the operation of forming theterminal 110. Instead, as discussed above, both structures can be formedas part of the same operation. Still further, as discussed above, thevia 140 can be formed using processes that produce non-scalloped,generally uniform, flat, cylindrical walls. For example, a continuous,anisotropic etch process can be used to produce the via 140. As aresult, the via 140 can be less time consuming to form than vias thatuse alternating etch processes, and can use the limited volume availablein the substrate 120 more efficiently than processes that producecontoured and/or non-uniform walls.

FIGS. 3A-3F illustrate representative processes for forming conductiveterminals having shapes in accordance with further embodiments of thedisclosure. Referring first to FIG. 3A, a via 140 is formed in asubstrate 120 using processes generally similar to those describedabove. A terminal opening 311 can then be formed at the bottom of thevia 140, using processes that may form shapes other than the generallyspherical shape described above. For example, an anisotropic etchprocess can be used to remove substrate material 121 in a manner that isaligned with crystal planes of the substrate material 121, producing aterminal opening 311 having generally flat sidewalls. Representativeprocesses for forming such openings are discussed in de Boer et al.(March 2000), previously incorporated by reference.

In FIG. 3B, a dielectric layer 125, a barrier layer 126, and an optionalseed layer 127 have been disposed in the via 140 and the terminalopening 311. The via 140 and the terminal opening 311 have then beenfilled with a conductive material 112 using any of the foregoingprocesses described above with reference to FIG. 2F. Material from thesecond surface 124 of the substrate 120 is then removed to form a firstterminal 310 a having an exposed surface 318.

FIG. 3C illustrates a second terminal 310 b formed by removingadditional substrate material 121 in a manner generally similar to thatdescribed above with reference to FIG. 2H. Accordingly, the secondterminal 310 b can include outwardly facing surfaces 313 that projectbeyond the second surface 124. The second terminal 310 b can include anadditional conductive material, for example, a flash coating (asdiscussed above with reference to FIG. 2H) or a solder ball (asdiscussed above with reference to FIG. 2I).

FIG. 3D illustrates a third terminal 310 c configured in accordance withanother embodiment of the disclosure. In this embodiment, thebackgrinding process has been halted prior to removing any of theconductive material 112 within the terminal opening 311. The substratematerial 121 has been selectively removed from around the conductivematerial 112 in the terminal opening 311 to form the illustratedstructure. For example, the substrate 120 can be exposed to an etchantthat preferentially removes the substrate material 121 (and possibly thedielectric material 125 and the barrier layer 126) while not removingthe conductive material 112 and optionally the seed layer 127. Thisarrangement can produce a third terminal 310 c that projects beyond thesecond surface 124 by an additional amount and provides an additionalvolume of conductive material 112 at the third terminal 310 c forconnecting the substrate 120 to adjacent structures.

FIGS. 3E and 3F illustrate another process for forming a terminal inaccordance with another embodiment of the disclosure. As shown in FIG.3E, in some cases, the conductive material 112 applied to the surfacesof the terminal opening 311 and the via 140 may leave a void 316, e.g.,in the terminal opening 311. While voids are generally undesirable inmost semiconductor processing operations, the void 316 shown in FIG. 3Emay be readily accommodated and/or accounted for. For example, as shownin FIG. 3F, when the substrate material 121 is removed from the secondsurface 124 to uncover the exposed surface 318, the void 316 is alsoexposed. Optionally, the void 316 can then be filled with a secondconductive material 317. For example, the void 316 can be filled orpartially filled with a flash coating, and the shape and additionalsurface area of the void 316 can facilitate a strong physical andelectrical connection with the coating. In another embodiment, the void316 can be left intact and can be used to receive conductive materialfrom a corresponding terminal structure of a neighboring (e.g., stacked)substrate. For example, the void 316 can receive and connect with asolder ball or other terminal (e.g., the second terminal 110 b or thethird terminal 110 c shown in FIGS. 2H, 2I respectively) from aneighboring substrate.

FIG. 4 illustrates another embodiment for forming the vias 140 in thesubstrate 120. In this embodiment, a protective layer 422 is applied tothe first surface 123 of the substrate 120, and to the sidewall surfaces141 of the vias 140. In some cases, the via 140 may have a high aspectratio (e.g., a relatively long length and/or relatively small width),which can cause the protective layer 422 to more readily attach to thesidewall surfaces 141 than to the end surface 142. As a result, the endsurface 142 may receive little or no protective material 422. Thisarrangement can eliminate the need to remove the protective layer 422from the end surface 142 and instead, a terminal opening can be formeddirectly after applying the protective layer 422. As a result,embodiments of this process are expected to reduce the amount of timerequired to form the conductive terminals, and can thereby reduce thecost of forming the dies or other end products from the substrate 120.

Any of the semiconductor packages resulting from joining the substratesin accordance with the methods described above with reference to FIGS.1-4 can be incorporated into a myriad of larger and/or more complexsystems, a representative example of which is a system 500 shownschematically in FIG. 5. The system 500 can include a processor 552, amemory 554 (e.g., SRAM, DRAM, flash memory and/or other memory device),input/output devices 556 (e.g., a sensor and/or transmitter), and/orother subsystems or components 558. Semiconductor packages having anyone or a combination of the features described above with reference toFIGS. 1-4 may be included in any of the devices shown in FIG. 5. Theresulting system 500 can perform any of a wide variety of computing,processing, storage, sensing, imaging, and/or other functions.Accordingly, the representative system 500 can include withoutlimitation, computers and/or other data processors, for example, desktopcomputers, laptop computers, Internet appliances, hand-held device(palm-top computers, wearable computers, cellular or mobile phones,personal digital systems, music players, cameras, etc.), multi-processorsystems, processor-based or programmable consumer electronics, networkcomputers and mini-computers. Other representative systems 500 may behoused in a single unit or distributed over multiple interconnectedunits (e.g., through a communication network). The components of thesystem 500 can accordingly include local and/or remote storage devices,and any of a wide variety of computer-readable media.

From the foregoing, it will be appreciated that specific embodiments ofthe disclosure have been described for purposes of illustration, butthat the foregoing systems and methods may have other embodiments aswell. For example, while certain of the embodiments described above weredescribed in the context of semiconductor packages having two or threestacked dies, in other embodiments, the packages can include othernumbers of stacked dies. In some cases, the via 140 may not extendcompletely through the substrate, e.g., if the substrate forms thetopmost die shown in FIG. 1. In such cases, the via 140 may still beused for thermal purposes, e.g., to act as a heat conduit or heat sink.The same processes described above can be used to form the via andterminal, but the terminal is not exposed at the second surface of thesubstrate. Such substrates can also be used for planar (unstacked) dies.In other embodiments, the terminal can be exposed to connect the planar(unstacked) die to PCBs or other support members or substrates. Many ofthe processes for forming the foregoing connected structures andconnecting the mating structures of different semiconductor substratescan be carried out at the die level (e.g., after singulating the dies),the wafer level (e.g., before singulating the dies) and/or otherprocessing stages.

Certain features described in the context of particular embodiments maybe combined or eliminated in other embodiments. For example, the processof coating the sidewall surfaces described above with reference to FIG.4 can be applied to vias formed in association with the conductivestructures shown in any of the other Figures. The process of removingsubstrate material from around the entire terminal opening, as shown inFIGS. 3C and 3D, can be applied to the terminal openings shown in FIG.2E or 2H. Further, while features and results associated with certainembodiments have been described in the context of those embodiments,other embodiments may also exhibit such features and results, and notall embodiments need necessarily exhibit such features and results.Accordingly, the disclosure can include other embodiments not expresslyshown or described above.

We claim:
 1. A method for forming a semiconductor assembly, comprising:forming a blind via in a semiconductor substrate, the via including asidewall surface and an end surface; applying a protective layer to thesidewall surface of the via; forming a terminal opening by selectivelyremoving substrate material from the via at the end surface whileprotecting from removal substrate material against which the protectivelayer is applied; disposing a conductive material in both the via andthe terminal opening to form an electrically conductive terminal that isunitary with conductive material in the via; removing substrate materialadjacent to the terminal to expose the terminal; and electricallyconnecting the terminal to a conductive structure external to thesubstrate.
 2. The method of claim 1: wherein disposing a conductivematerial includes forming a homogenous conductive structure by disposinga solderless conductive material in the via during a via dispositionprocess and disposing the solderless conductive material in the terminalopening during a terminal disposition process, without realigning thesemiconductor substrate relative to a source of the conductive materialbetween the via and the terminal disposition processes; wherein theprocess of removing substrate material from the via at the end surfaceis performed without removing substrate material from the sidewalllayer; wherein the semiconductor substrate includes a firstsemiconductor die and wherein electrically connecting the terminal to aconductive structure includes connecting the terminal to a secondsemiconductor die in a stacked arrangement with one die facing towardthe other; wherein the via is elongated along a via axis; whereinremoving substrate material adjacent to the terminal includes exposing alaterally outwardly facing surface of the terminal; and wherein themethod further comprises applying an additional conductive materialwithout using a mask at the second surface to the terminal.
 3. Themethod of claim 1 wherein the semiconductor substrate has a firstsurface and a second surface facing opposite from the first surface, andwherein the via extends into the semiconductor substrate from the firstsurface, further wherein forming an electrically conductive terminalincludes forming the electrically conductive terminal without using amask at the second surface.
 4. The method of claim 1 wherein disposing aconductive material includes disposing the conductive material in thevia during a via disposition process and disposing the conductivematerial in the terminal opening during a terminal disposition process,without realigning the semiconductor substrate relative to a source ofthe conductive material between the via and the terminal dispositionprocesses.
 5. The method of claim 1 wherein the semiconductor substrateincludes a semiconductor die and wherein electrically connecting theterminal to a conductive structure includes connecting the terminal to asupport member.
 6. The method of claim 1 wherein the semiconductorsubstrate includes a first semiconductor die and wherein electricallyconnecting the terminal to a conductive structure includes connectingthe terminal to a second semiconductor die.
 7. The method of claim 1wherein applying the protective layer includes applying the protectivelayer to both the side surface and the end surface, and wherein themethod further comprises removing the protective layer from the endsurface before forming the terminal opening.
 8. The method of claim 1wherein applying the protective layer includes completing application ofthe protective layer to the sidewall surface without applying theprotective layer to the end surface of the via.
 9. The method of claim 1wherein the conductive material is a first conductive material andwherein the method further comprises applying a second conductivematerial to the first conductive material before electrically connectingthe terminal to the conductive structure.
 10. The method of claim 9wherein applying the second conductive material includes applying aflash coating.
 11. The method of claim 9 wherein applying the secondconductive material includes applying a solder ball.
 12. The method ofclaim 11 wherein the via is elongated along a via axis, and whereinremoving substrate material includes exposing a laterally outwardlyfacing surface of the terminal, and wherein applying the solder ballincludes applying the solder ball so that it contacts the exposed,laterally outwardly facing surface of the terminal.
 13. The method ofclaim 1 wherein forming a terminal opening includes forming a terminalopening having generally flat sides positioned along crystal planes ofthe substrate material.
 14. The method of claim 1 wherein forming aterminal opening includes forming a concave, cup-shaped opening.
 15. Themethod of claim 1 wherein forming a via includes forming a via withgenerally smooth, non-scalloped sidewalls.
 16. The method of claim 1wherein disposing a conductive material includes disposing at least oneof copper having a purity of at least 90%.
 17. The method of claim 1wherein electrically connecting the terminal includes electricallyconnecting the terminal without reflowing the conductive material.
 18. Amethod for forming a semiconductor assembly, comprising: forming anopening in a first major surface of a semiconductor substrate, thesemiconductor substrate having a second major surface facing away fromthe first major surface, the opening having a via portion with firstwidth at the first surface, the opening further having a terminalportion with a second width greater than the first width at the secondsurface; and disposing a conductive material in the opening at the viaportion and the terminal portion, without using a masking process at thesecond surface, and without venting the opening at the second surface,the conductive material being a homogenous, solderless material.
 19. Themethod of claim 18 wherein the semiconductor substrate is a firstsemiconductor substrate, and wherein the method further comprisesstacking a second semiconductor substrate relative to the firstsemiconductor substrate and electrically connecting the conductivematerial at the terminal portion of the first semiconductor substrate toa terminal of the second semiconductor substrate.
 20. The method ofclaim 18 wherein forming an opening includes forming a via portionhaving a sidewall surface and an end surface, applying a protectivelayer to the sidewall surface, and removing material from the endsurface to form the terminal portion.